Vol. 61, Issue 3, 614-619, March 2002

Regulation of Cyclooxygenase-2 Expression by Phospholipase D in Human Amnion-Derived WISH Cells

Dae-Won Park, Yoe-Sik Bae, Ju-Ock Nam, Jong-Ho Kim, Young-Gi Lee, Yoon-Ki Park, Sung Ho Ryu, and Suk-Hwan Baek

Departments of Biochemistry and Molecular Biology (D.-W.P., J.-O.N., S.-H.B.) and Obstetrics and Gynecology (Y.-G.L., Y.-K.P.), College of Medicine, Yeungnam University, Daegu, Korea; Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, Korea (Y.-S.B., S.H.R.); and Department of Obstetrics and Gynecology, College of Medicine, Dongguk University, Kyungju, Korea (J.-H.K.)

Prostaglandins (PGs) are known to play a key role in the initiation of labor, but the mechanisms regulating their synthesis in amnion are largely unknown. In this study, the regulatory mechanisms for PGE₂ production during phospholipase D (PLD) and p38-dependent activation of WISH cells were investigated. We found that the stimulation of WISH cells with interleukin (IL)-1 elicited dose-dependent synthesis of cyclooxygenase-2 (COX-2) mRNA, protein, and their products, PGE₂. Moreover, the treatment of [³H]myristate-labeled cells in the presence of 1-butanol caused the dose-dependent formation of [³H]phosphatidylbutanol (PBt), a product specific to PLD activity. Pretreating the cells with 1-butanol and Ro 31-8220 inhibited the IL-1-induced COX-2 expression, but 3-butanol did not affect this response. In addition, evidence that PLD was involved in the stimulation of COX-2 expression was provided by the observations that COX-2 expression was stimulated by the dioctanoyl phosphatidic acid (PA) and that the prevention of PA dephosphorylation by 1-propranolol potentiated COX-2 expression by IL-1. Moreover, IL-1 stimulation of the cells caused the phosphorylation of p38 and extracellular signal-regulated kinase (ERK), and IL-1-induced COX-2 expression was inhibited by the pretreatment of WISH cells with a p38 inhibitor, in contrast ERK upstream inhibitor had no effect. Furthermore, Ro 31-8220 inhibited IL-1-induced p38 phosphorylation but not ERK phosphorylation. The results of this study indicate that in human amnion cells, IL-1 might activate PLD through an upstream protein kinase C to elicit p38 and finally induce COX-2 expression.